This invention concerns locking devices and methods, more particularly such devices and methods as applied to covers used for catch basins and manholes installed in roadways for access to utilities, i.e., water, gas, communications, electricity. These covers are provided in order to keep out debris but also to present a supporting surface for pedestrians and vehicles on the surrounding roadway surface. If the covers are removed, the opening to a catch basin or manhole presents a severe hazard to vehicles and pedestrian traffic. Removal of these covers by vandals or scavengers has become an increasing problem which has created an urgent need for some means for securing the covers in place. There are no locking devices incorporated in existing catch basin and manhole covers such that providing a simple retrofit for existing covers is highly desirable. Such devices must be rugged to withstand traffic and weather and the efforts of vandals or terrorists to remove them. The large numbers involved dictate a simple installation method to minimize labor costs. The device must not present an obstruction in the roadway, particularly for snow plows, nor a tripping hazard to pedestrians.
It is the object of the present invention to provide a locking device and method which can quickly be installed to provide a simple retrofit to existing manhole and catch basin covers.
It is a further object to provide such a device which is rugged and able to withstand abuse and heavy traffic and reliably secure such covers in place without creating an obstruction in the roadway.
These objects and others which will be appreciated upon a reading of the following specification and claims are achieved by providing a locking device insertable into an opening in the cover adjacent a sidewall of the cover frame. The device is comprised of an upper and a lower member which are connected to each other end-to-end so as to allow articulation of the lower member to install the device, the members are initially set in an end-to-end alignment and are inserted into the cover opening. The members are held in end to end alignment with a detent mechanism including interfit detent features and the respective members held in that position by one or more springs so as to connected exert a force pulling the members together to maintain the interfit detent features in engagement.
A bolt having a tamper resistant head extends through a hole in the upper member and is left hand threadably received in a trunnion member rotatably mounted to the lower member extending across a space defined by space sidewalls included in the lower member. The bolt can be pushed down against a bottom wall of the upper member to counter the spring force and thereby allowing disengagement of the interfit detent features. The spring or springs then cause the lower member to be pivoted on the trunnion with respect to the upper member and thereby angled towards the sidewall adjacent the opening until the bottom end of the lower member engages the same. Teeth are preferably formed along the bottom end edge of the lower member engaged with the sidewall.
Notch contours on the upper end of the lower member at the same time are moved to engage an edge of the cover opening through which the device is inserted.
The bolt is then driven on its threaded connection to the trunnion by a special tool socket to draw the lower member up, the upper member having a flange overlying the cover to provide a reaction surface. This creates a powerful wedging of the lower member between the sidewall and opening edge, preventing lifting of that side of the cover. By installing four locking devices, two on each side of the cover, the cover is wedged securely in its opening to prevent its removal.
The bolt head is received within a recess in the top of the upper member and has driving contour requiring a special tool to prevent removal of the locking device by the use of standard tools.
A plastic cap is placed over the bolt head and in the recess to prevent weathering of the bolt threads and the entrance of plugging dirt and debris. Special features on the cap provide a tamper indication if the cap is removed.
A special version of the device is used for manhole covers, in which an adapter sleeve is fitted into a round hole bored into the manhole cover and secured to the cover with bolts received in threaded holes formed into the underside of the manhole cover. The upper member is received in a central rectangular opening in the adapter sleeve, the upper member having a round flange smoothly overlying the adapter sleeve top surface adjacent the rectangular opening.
An extension arm is secured to the bottom end of the lower member to enable the toothed bottom edge of the extension arm to reach a sidewall edge located further from the manhole cover opening in which the locking device is inserted. The extension arm is attached using a pivot bolt and a shear pin so that the cover can be released and blown free in the event of a gas explosion to prevent structural damage. The adapter sleeve presents an opening wall which projects downwardly to present an edge engageable with the lower member notched contours to establish a wedging lock as in the catch basin version of the locking device.
A special radio signaling device can also be built into the cap, able to provide a remote alarm via a repeater amplification to a central station if tampering is detected, which can also be used to locate a catch basin or manhole when a cover has been removed or tampered with.